Numerous studies have been conducted to determine the efficacy of nutritional supplements on exercise performance. A glycine and L-arginine salt of alpha-ketoisocaproic acid dicalcium (GAKIC), has been demonstrated to enhance anaerobic exercise performance with no reported side effects. No study has examined supplementing the individual components of GAKIC prior to anaerobic exercise performance. PURPOSE To determine whether ketoisocaproic acid (KIC), a component of GAKIC, affects anaerobic exercise performance. METHODS Fourteen resistance trained, college aged males (22.78 ± 2.6 years) participated in a double blind, placebo controlled, latin square crossover designed experiment. All subjects were pre-tested for maximal strength (1-RM) and muscle endurance (50% 1RM repetitions to muscular failure) on two exercises (seated chest press and leg press). Repetition speed was controlled with a metronome during muscular endurance testing. Each subject participated in four testing sessions separated by 7 days, two with low dose supplementation (1.5g KIC or 1.5g isocaloric placebo) and two with high dose supplementation (9.0g KIC or 9.0g isocaloric placebo), in a randomized manor. Each supplement was consumed in two equal doses 45 minutes prior to exercise testing. Following supplementation, subjects completed chest press and leg press muscular endurance testing. Total number of repetitions completed at 50% 1RM and total volume lifted for each exercise was compared using one-way repeated measures ANOVAs. RESULTS No significant difference was observed between conditions for number of repetitions performed for the chest press low dose (18 ± 3 vs. 18 ± 3, p = 0.51), leg press low dose (20 ± 5 vs. 21 ± 7, p = 0.48), chest press high dose (18 ±3 vs. 18 ±4, p = 0.65), or leg press high dose (20 ± 4, vs. 22 ± 8, p = 0.17). Further, no significant difference was observed for number of repetitions performed between the high and low KIC conditions for the chest press (p = 0.30) or the leg press (p = 0.34). CONCLUSION Oral KIC supplementation 45 minutes prior to resistance exercise does not appear to improve muscle endurance.